1. Field of the Invention
The invention relates to a panel structure of a plasma display panel.
2. Description of the Related Art
Recent years, a plasma display panel of a surface discharge scheme AC type as an oversize and slim display for color screen has been received attention, which is becoming widely available.
FIG. 8 is a schematically front view illustrating a conventional surface discharge scheme AC type plasma display panel. FIG. 9 is a sectional view taken along the V3xe2x80x94V3 line of FIG. 8. FIG. 10 is a sectional view taken along the W3xe2x80x94W3 line of FIG. 8. FIG. 11 is a sectional view taken along the W4xe2x80x94W4 line of FIG. 8.
In FIGS. 8 to 11, on the backside of a front glass substrate 1 to serve as a display screen of the plasma display panel, there is sequentially provided with a plurality of row electrode pairs (Xxe2x80x2, Yxe2x80x2); a dielectric layer 2 overlaying the row electrode pairs (Xxe2x80x2, Yxe2x80x2); and a protective layer 3 made of MgO which overlays a backside of the dielectric layer 2.
The row electrode Xxe2x80x2 consists of a T-shaped transparent electrode Xaxe2x80x2 which is composed of a widened distal end Xa1xe2x80x2 formed of a transparent conductive film made of ITO or the like and a narrowed linking portion Xa2xe2x80x2, and a bus electrode Xbxe2x80x2 formed of a metal film, extending in the row direction and connected to the linking portions Xa2xe2x80x2 of the transparent electrode Xaxe2x80x2.
The row electrode Yxe2x80x2, similarly, consists of a T-shaped transparent electrode Yaxe2x80x2 which is composed of a widened distal end Ya1xe2x80x2 formed of a transparent conductive film made of ITO or the like and a narrowed linking portion Ya2xe2x80x2, and a bus electrode Ybxe2x80x2 formed of a metal film, extending in the row direction and connected to the linking portions Ya2xe2x80x2 of the transparent electrode Yaxe2x80x2.
The row electrodes Xxe2x80x2 and Yxe2x80x2 are alternated on the front glass substrate 1 in the column direction (in the vertical direction of FIG. 8). Concerning the transparent electrodes Xaxe2x80x2 and Yaxe2x80x2 of the row electrode pair (Xxe2x80x2, Yxe2x80x2) aligned along the respective bus electrodes Xbxe2x80x2 and Ybxe2x80x2, each of the transparent electrodes Xaxe2x80x2 and Yaxe2x80x2 extends toward the pair to the row electrode Xxe2x80x2 or Yxe2x80x2. Therefore, the tops of the respective widened distal ends Xa1xe2x80x2 and Ya1xe2x80x2 oppose each other to interpose a discharge gap gxe2x80x2, having a predetermined width, between them.
Each row electrode pair (Xxe2x80x2, Yxe2x80x2) forms a display line (row) L for matrix display.
The front glass substrate 1 faces a back glass substrate 4 with a discharge space Sxe2x80x2, filled with a discharge gas, in between.
The back glass substrate 4 is provided with a plurality of column electrodes Dxe2x80x2 arranged to extend in a direction perpendicular to the row electrode pairs Xxe2x80x2 and Yxe2x80x2; band-shaped partition walls 5 each extending between the adjacent column electrodes Dxe2x80x2 in parallel; and a phosphor layer 6 consisting of a red phosphor layer 6(R), green phosphor layer 6(G) and blue phosphor layer 6(B) and overlaying side faces of the partition walls 5 and the column electrodes Dxe2x80x2.
In each display line L, the partition walls 5 divide a discharge space Sxe2x80x2 at each intersection of the column electrode Dxe2x80x2 and the row electrode pair (Xxe2x80x2, Yxe2x80x2) to defines discharge cells Cxe2x80x2.
As illustrated in FIG. 9 and FIG. 10, in the plasma display panel, on portion of the backside of the dielectric layer 2 which faces the bus electrodes Xbxe2x80x2 and Ybxe2x80x2 oriented back to back and extending in parallel, an additional dielectric layer 2A is formed to extend in parallel along the bus electrodes Xbxe2x80x2, Ybxe2x80x2.
The additional dielectric layer 2A is formed to protrude from the backside of the dielectric layer 2 into the discharge space Sxe2x80x2. The additional dielectric layer 2A has the function of limiting the spread of a surface discharge d, caused between the opposite transparent electrodes Xaxe2x80x2 and Yaxe2x80x2 in the discharge space Sxe2x80x2, toward the bus electrodes Xbxe2x80x2 and Ybxe2x80x2 so as to prevent occurrence of a false discharge between the discharge cells Cxe2x80x2 adjacent to each other in the column direction.
In the above surface discharge scheme AC type plasma display panel, an image is displayed as follows:
First, through addressing operation, discharge (opposite discharge) is caused selectively between the row electrode pairs (Xxe2x80x2, Yxe2x80x2) and the column electrodes Dxe2x80x2 in the respective discharge cells Cxe2x80x2, to scatter lighted cells (the discharge cell in which wall charge is formed on the dielectric layer 2) and nonlighted cells (the discharge cell in which wall charge is not formed on the dielectric layer 2), over the panel in accordance with the image to be displayed.
After the addressing operation, in all the display lines L, the discharge sustain pulses are applied alternately to the row electrode pairs (Xxe2x80x2, Yxe2x80x2) in unison, and thus, in the lighted cell, a surface discharge is caused in a space between a pair of additional dielectric layers 2A, which are adjacent to each other with the lighted cell in between, on every application of the discharge sustain pulse. The above surface discharge generates ultraviolet radiation, and thus the corresponding red(R), green (G) and/or blue (B) phosphor layers 6 in the discharge space Sxe2x80x2 are excited to emit light, resulting in forming the display image.
As explained above, in the conventional plasma display panel (PDP), the additional dielectric layer 2A formed in the portion facing the bus electrodes Xbxe2x80x2, Ybxe2x80x2 to extend in the row direction, limits the spreading of the discharge in the column direction in order to prevent occurrence of interference between discharges in the discharge cells Cxe2x80x2 adjacent to each other in the column direction.
In the above conventional PDP, however, since the additional dielectric layer 2A is formed in such a manner that a glass paste is screen-printed on the backside of the dielectric layer 2, and is dried and then further burned, an edge portion 2Aa of the additional dielectric layer 2A is limp to form a gentle slop. Therefore, the edge portion 2Aa overlaps end portions Xa2xe2x80x3, Ya2xe2x80x3 of the respective linking portion Xa2xe2x80x2, Ya2xe2x80x2 of the transparent electrodes Xaxe2x80x2, Yaxe2x80x2, respectively connected to the bus electrodes Xbxe2x80x2, Ybxe2x80x2 (an area indicated with xe2x80x9cnxe2x80x9d in FIG. 9).
For this reason, when an image is formed, the discharge decreases on the end portions Xa2xe2x80x3, Ya2xe2x80x3 of the linking portions Xa2xe2x80x2, Ya2xe2x80x2 of the respective transparent electrodes Xaxe2x80x2, Yaxe2x80x2, thereby to decrease the efficiency of light emission in this area.
Hence, there is a problem of the decreased efficiency of light emission in the entire discharge cell C.
The surface discharge caused in the discharge cell C in formation of an image may cross over the gently sloped edge portion 2Aa of the additional dielectric layer 2A to spread out into another adjacent discharge cell C in the column direction. This may produce interference of discharge between the two adjacent discharge cells C in the column direction. In the event of the interfering discharges, lighted and unlighted discharge cells may be reversed to produce an instable and inaccurate image.
The present invention has been made to solve the disadvantages associated with the conventional plasma display panel as described above.
It is therefore an object of the present invention to provide a plasma display panel which is capable of improving the efficiency of light emission in each discharge cell, and also effectively preventing interference of discharge from occurring between the adjacent discharge cells to display stable images.
To attain the above objects, a plasma display panel according to a first invention includes a plurality of row electrode pairs extending in a row direction and arranged in a column direction to form display lines and a dielectric layer overlaying the row electrode pairs on a backside of a front substrate, and a plurality of column electrodes extending in the column direction and arranged in the row direction on a back substrate facing the front substrate via a discharge space, unit light emitting areas being formed in the discharge space at respective intersections of the column electrodes and the row electrode pairs. Such plasma display panel features in that: an additional portion is formed on a backside of the dielectric layer to protrude to the inside of the discharge space and extend along an edge of the unit light emitting area extending in parallel to the row direction; in that each row electrode of the row electrode pair has a bus electrode extending along the edge of the unit light emitting area in the row direction, and transparent electrodes connected to the bus electrode and each extending toward the mate of the row electrode of the row electrode pair for each unit light emitting area, the transparent electrode of each one row electrode opposing to the transparent electrode of the other row electrode via a gap having a predetermined width; and in that when viewed from the front substrate, an overlap portion of a proximal end of the transparent electrode of each of the row electrode connected to the bus electrode, which overlaps the additional dielectric layer, is designed to be smaller in width than that of a portion between the overlap portion and a distal end of the transparent electrode.
In the plasma display panel according to the first invention, an image is formed by selectively performing a discharge between the transparent electrodes opposing to and paired with each other in each unit light emitting area. The portion of the proximal end of the transparent electrode of each row electrode which is connected to the bus electrode overlaps the additional dielectric layer for prevent a false discharge. The above overlapping portion has a width smaller than that of the portion between the overlapping portion and the distal end. For this reason, in the discharge, the discharge is decreased in the overlapping portion between the transparent electrode and the additional dielectric layer, and performed mainly in the distal ends of the respective transparent electrodes which are paired with and face each other.
In consequence, according to the first invention, the additional dielectric layer less obstructs a discharge caused in forming an image. This improves the efficiency of light emission. Further, since the discharge for forming an image is performed mainly in a central portion of each unit light emitting area, the discharge is limited going beyond the additional dielectric layer to spread out into an adjacent unit light emitting area in the column direction to prevent occurrence of the false discharge.
To attain the aforementioned object, the plasma display panel according to a second invention features, in addition to the configuration of the first invention, in that the transparent electrode is formed in an approximately T-shape by a widened portion opposing to the pair of the transparent electrode, and a narrowed portion linking the widened portion to the bus electrode and having a smaller width than that of the widened portion, wherein a portion of the narrowed portion overlapping the additional dielectric layer is designed to be further smaller in width than that of a distal portion of the narrowed portion on the widened portion side.
According to the plasma display panel of the second invention, the overlap portion of the narrowed portion of the approximately T-shaped transparent electrode linking the widened portion with the bus electrode, which overlaps the additional dielectric layer, is formed to be further smaller in width than that of another portion of the narrowed portion on the widened portion side. As a result, since a discharge is decreased on the overlap portion of the transparent electrode with the additional dielectric layer, the efficiency of light emission is improved and occurrence of a false discharge is prevented by limiting the spread of the discharge going beyond the additional dielectric layer into another adjacent unit light emitting area in the column direction.
To attain the aforementioned objects, the plasma display panel according to a third invention features, in addition to the configuration of the first invention, in that a width of the transparent electrode is decreased gradually from the distal end thereof toward the proximal end thereof connected the bus electrode.
According to the plasma display panel of the third invention, in the connection side of the transparent electrode with the bus electrode, the overlap portion with the additional dielectric layer is smaller in width than that of the distant end of the transparent electrode. As a result, since a discharge is decreased on the overlap portion of the transparent electrode with the additional dielectric layer, the efficiency of light emission is improved and occurrence of a false discharge is prevented by limiting the spread of the discharge going beyond the additional dielectric layer into another adjacent unit light emitting area in the column direction.
To attain the aforementioned objects, the plasma display panel according to a fourth invention features, in addition to the configuration of the first invention, in that an a really enlarged portion is formed in a portion of the proximal end of the transparent electrode overlaying the bus electrode for connection.
According to the plasma display panel of the fourth invention, due to the smaller width of the overlap portion of the proximal end of the transparent electrode with the additional dielectric layer, the efficiency of light emission is improved and occurrence of a false discharge is prevented.
In the plasma display panel, due to a small width of the proximal end of the transparent electrode connected to the bus electrode, the transparent electrode and the bus electrode easily separate from each other. For this reason, the a really enlarged portion is formed on the portion of the proximal end of the transparent electrode overlaying the bus electrode, thereby to prevent the transparent electrode and the bus electrode from separating from each other.
These and other objects and advantages of the present invention will become obvious to those skilled in the art upon review of the following description, the accompanying drawings and appended claims.